Project Summary This 2-site (Florida International University, Yale University) proposed funded Administrative Supplement to Pettit/Silverman R01, Targeting Attention Orienting to Social Threat to Reduce Social Anxiety in Youth, aims to increase the sustained impact of the project and falls within the scope of the current award. Our primary aim is to collect Supplemental data to firmly establish stability of the study's putative target mechanism, the rapidly deployed attention-associated neural processes measured via event-related potentials (ERPs) (i.e., P1 amplitudes for socially threatening stimuli in peri-pubertal youth ages 10 to 14 years). We will collect Supplemental data using a broadened sampling frame of 70 additional youths (35 per site) across a continuum of social anxiety symptom severity, in line with the Research Domain Criteria (RDoC) framework. We will use the same Parent Grant assessment points: PRE, MID (two weeks after PRE), POST (four weeks after PRE), and FOLLOWUP (6 Months after POST). The Supplemental participants will be involved only in the study's assessment procedures, unlike Parent Grant participants who are randomized to either (1) Attention Bias Modification Treatment (ABMT) or (2) Neutral Control Task (NCT). We will evaluate (1) within-subject stability among the Supplemental participants who receive no intervention, and (2) between-subject stability by comparing Supplemental participant data with Parent Grant participant data. There has never been a stability study of our project's putative target P1 amplitudes for socially threatening stimuli in youth (or adults), aside from our preliminary data (test-retest reliability of r = .50 over 8 weeks). Collecting these Supplemental data is therefore critical to establish firmly the target's stability and will benefit the experimental therapeutics approach by providing novel confirmatory support for the mechanistic role of ERP P1 amplitudes in attention training protocols in a broad sample of youth whose social anxiety symptoms are assessed dimensionally. Data documenting within-subject stability among Supplemental participants, together with data from the Parent Grant demonstrating P1 reductions in youth who receive attention training, would provide novel convergent data, establishing more firmly the stability and plasticity of this target in the critical developmental window of peri-puberty. These data will further facilitate our efforts to translate ERP effects from the Parent Grant into clinically interpretable effects. This is because these Supplemental data from a broadened sample of youth across a continuum of social anxiety severity will provide a benchmark against which to compare ERP P1 amplitudes in youth with social anxiety disorder prior to attention training. They also will allow us to determine whether attention training in youth with social anxiety disorder results in ERP P1 amplitudes comparable with those found in a broadened, nonreferred sample of youth, and whether this occurs after 4 (MID) or 8 sessions (POST).